VOCs are common material components of the atmosphere with many sources. Common sources include fueling stations for vehicles, industrial and commercial degreasers, paint shops, and other sources. These VOCs include compounds such as mono and polycyclic aromatic hydrocarbons (e.g., benzene, toluene, xylene, naphthalene, etc.), halogenated hydrocarbons (e.g., trichloroethylene (TCE), carbon tetrachloride (CT)), and aliphatic hydrocarbons (e.g., hexane or octane)
A wide array of sensors have been developed and are commercially available to detect and quantify the amount and type of VOCs for use by workers, first responders, and others involved in safety inspection or handling of these materials. Several methods are employed in commercially available sensors including: photoionization detection (PID); flame ionization detection (FID); non-dispersive IR/absorption detection (NDIR); thermal conductivity (TC); hot wire or hot semiconductor detection; and electrochemical detection. None of these methods is specific to naphthalene, benzene, toluene, xylene, and several other hazardous VOCs.
Naphthalene exposure to personnel working in the vicinity of JP8 or other naphthalene-bearing jet fuels has been shown to cause physical damage to lung tissue and potentially cause genetic damage under prolonged exposure as noted in Herrin, B. R., Haley, J. E., Lantz, R. C., Witten, M. L., “A reevaluation of the threshold exposure level of inhaled JP-8 in Mice”, Journal of Toxicological Sciences, v 31 3; p 219 (2006) and in Schreiner, C. A., “Genetic Toxicity of Naphthalene: A Review”, Journal of Toxicology and Environmental Health, Part B, v6 p 161 (2003). Exposure to naphthalene may occur through inhalation and dermal contact as noted in Egeghy, P. P., L. Hauf-Cabalo, R. Gibson, and S. M. Rappaport. “Benzene and naphthalene in air and breath as indicators of exposure to jet fuel. (Original Article).” Occupational and Environmental Medicine 60.12 (December 2003): 969(8) and in Chao, Y, E., Kupper, L. L., Serdar, B., Egeghy, P., Rappaport, S. M., Nylander-French, L. A., “Dermal exposure to Jet Fuel JP-8 significantly contributes to the production of urinary naphthols in fuel-cell maintenance workers”, Environmental Health Perspectives, v 114, no 2, p 182-185 (2006). These deleterious effects from naphthalene have warranted closer monitoring to determine the daily exposure of individuals such that better methods to reduce exposure can be created. Although permissible exposure limits (PEL) for JP-8 are presently set at 350 mg/m3, recent studies have shown alterations in lung tissue with as little as 46 mg/m3.
Naphthalene is traditionally measured using typical analytical laboratory techniques such as various forms of gas chromatography, mass spectrometry, FTIR, and laser-induced fluorescence, or by field instruments such as photoionization or flame ionization based detectors. Laboratory techniques have high sensitivity and specificity, whereas present field instruments have very low levels of specificity. Because of the traditional size, weight, and power consumption of laboratory instruments, they are not suitable for significant miniaturization, and present field instruments have inadequate specificity in identifying naphthalene specifically.
A need exists for a method and compact apparatus for distinguishing selected VOCs, whether in a vapor, liquid, or solid state in the environment of interest, and more particularly for a compact, lightweight, portable detection methodology that can accurately assess the presence of such VOCs (e.g. naphthalene) at trace levels.